Evo-Devo in Ophiuroids: The Switch from Planktotrophy to Lecithotrophy in < em > Ophionereis < /em >

Biol Bull. 2023 Jun;244(3):164-176. doi: 10.1086/727755. Epub 2023 Oct 30.ABSTRACTAbstractUnderstanding the evolution of development (evo-devo) in the Ophiuroidea and the pathways in the switch from a feeding to a nonfeeding larva is complicated by the variability in the phenotype of the metamorphic larva, being a reduced yolky ophiopluteus in some species (type I development) and a vitellaria larva in others (type II development). We investigated evo-devo in the family Ophionereididae, a group dominated by lecithotrophic development through a vitellaria larva. We reared the planktotrophic larvae of Ophionereis fasciata to settlement to determine the metamorphic phenotype. Counter to expectations, O. fasciata did not exhibit type II metamorphosis through a vitellaria, although it did exhibit transient vitellaria-like features. Resorption of the larval arms in the same interradial positions where the ciliary bands form in vitellariae gave them a fleeting vitellaria-like appearance. Development of O. fasciata exhibits heterochronic features in early formation of the skeletal primordium of the third pair (postoral) of larval arms and in the presettlement juvenile early appearance of the juvenile terminal arm plates on external view in parallel with larval arm resorption. Development of the fourth pair (posterodorsal) of larval arms, the last pair to be formed, is plastic, with 44% of larvae exhibiting partial arm growth. Heterochronic traits in development, as seen in O. fasciat...

Source: The Biological Bulletin - March 8, 2024 Category: Biology Authors: Paulina Selvakumaraswamy Maria Byrne Source Type: research